Two powerfulsystems were targeting tens of millions of people across the U.S. on Tuesday. Heavy snow and high winds caused blizzard conditions in parts of the Plains and upper Midwest.
Some places had up to nine inches of snow with higher totals expected by the time the storm moves on.
To the east, crews were scrambling to repair downed power lines ahead of another massive winter storm.
More than 200,000 customers were still without electricity Tuesday morning after last week's.
The system was forming off the coast and was expected to reach the Northeast later Tuesday. It was expected to bring heavy snow and wind gusts up to 60 mph.
CBS News correspondent DeMarco Morgan reports from Sandwich, Massachusetts, that coastal flooding was a major concern.
Damage in the area left behind by last week's winter storm was still visible Tuesday. It brought wind gusts of up to 90 mph, dangerous storm surge and historic coastal flooding.
Officials in the area said more than 300 homes along the coast were at risk from the new storm.
In nearby Duxbury, 30 percent of the seawall was compromised, and officials were also concerned about flooding.
For communities away from the water, powerful gusts could knock out power to a region where more than 20,000 were still in the dark. Some homes may not have power restored until sometime this weekend.
Last week's nor'easter was blamed for nine deaths from Virginia to Massachusetts.
Though it's too early to detail specific impacts of the storm that will move east out of the Midwest, "this looks to be a significant event for at least a portion of the Northeast," said Frank Pereira, a meteorologist with the National Weather Service's Weather Prediction Center in College Park, Maryland. "A good swath of 6 to 12 inches of snow may fall across portions of the Northeast, and may include the Boston and New York areas."
Meanwhile, parts of the Dakotas were expected to get more than a foot of snow by the time the system moved east on Tuesday, with Minnesota, Nebraska and Iowa also getting significant amounts, according to the weather service.
State transportation officials advised against travel in parts of the upper Midwest, and a 211-mile stretch of Interstate 90 in southeastern South Dakota was shut down. I-29 also was set to shut down Monday evening from the North Dakota border to Iowa.
The Highway Patrol in Minnesota reported dozens of crashes, several with injuries. Crash reports were much lighter in the Dakotas, though there were numerous reports of vehicles sliding off icy highways.
"We've been really telling people not to drive, not to travel," South Dakota Department of Public Safety spokesman Tony Mangan said.
There were 120 flight cancellations and more than 300 delays at the Minneapolis airport as of late afternoon, according to Metropolitan Airports Commission spokesman Patrick Hogan.
Closures affected mostly elementary and secondary schools, though several colleges and universities also shut down their campuses for the day. Among them were the University of North Dakota and North Dakota State University, affecting more than 26,000 students. Those large schools don't often shut down due to weather.
"Safety is always the key factor," UND spokesman Peter Johnson said.
South Dakota Gov. Dennis Daugaard ordered state offices to close in 13 counties, though the Legislature was meeting as scheduled in Pierre. North Dakota's Human Services Department also shut down some outlying offices.